Essentially, most people you would meet are level 0 nerds. The people they feel uncomfortable around due to excessive nerdiness are level 1 nerds. The level 1 nerds feel uncomfortable around nerds of 2nd or higher level, etc.
Level 1: Has beaten it once.
Level 2: Has beaten it twice and has attended a fan club meeting or convention.
Level 3: Has beaten it so many times that the programmers call him for advice.
Level 4: Is the president of the RGS's fan club.